Aspects of the invention can relate to a projector which has a light modulation element for modulating light from a light source unit and a light adjusting unit for adjusting the amount of light incident on the light modulation element from the light source unit.
In the related art, a projector, which uses a liquid crystal display (LCD) as a light modulation element, has been suggested. In this case, in the LCD, liquid crystal molecules therein are displaced by controlling a voltage applied thereto and the gray-scale level of the LCD changes according to the displacement. Then, projected light is projected on a screen, such that an image is displayed. For example, when an image of a dark color system is displayed, the voltage to be applied is controlled in a low voltage region. In general, however, in such a projector, the displacement of the liquid crystal molecules is difficult to accurately control in the low voltage region, and thus, when an image is displayed in a high dynamic range including a dark color region, the gray-scale level of the LCD is difficult to accurately control.
In order to solve this problem, a projection-type display device disclosed in Japanese Unexamined Patent Application Publication No. 2001-100699 (page 8 and FIG. 10) has been suggested. This related art projection-type display device has an illumination-light modulating unit, such as an iris or the like, that is provided between a light source and an optical modulator, such as a liquid crystal display panel or the like. In this related art projection-type display device, the amount of light incident on the liquid crystal display panel can be adjusted according to luminance of an image to be displayed by controlling the illumination-light modulating unit. For this reason, for example, when the image of the dark color system is displayed, the amount of light incident on the liquid crystal display panel is decreased, such that an image can be displayed in a high dynamic range.
In the projection-type display device according to the related art, there are problems described below. In the projection-type display device, for example, the amount of light incident on the liquid crystal display panel is adjusted by use of the illumination-light modulating unit having the iris. However, when the amount of light is adjusted in such a manner, the amount of light incident on the liquid crystal display panel may be made nonuniform, which causes luminance irregularity (shading) or color irregularity (hereinafter, collectively referred to as ‘display irregularity’) in the displayed image.
Here, in the projection-type display device according to the related art, a light source driving circuit that directly adjusts luminance of a light source may be provided, instead of the above-described illumination-light modulating unit. However, when luminance of the light source is directly adjusted, the operation of the light source may be made unstable, and the adjustment range of luminance of the light source may narrow. Accordingly, when the image of the dark color system is displayed, the luminance control may be made unstable and brightness may be changed.